Method of and apparatus for controlling concentration



1942- M. c. HANSON A 2,290,471

METHOD OF AND APPARATUS FOR CONTROLLING CONCENTRATION Filed Aug. 5, 1939 v' 4Sheets-S heefil July 21, 1942. M. c. HANSON ETAL 2,290,471

1 mmnon OF AND APPARATUS FOR CONTROLLING coucmwmmou v Filed Aug 5, 1959 4 Sheets-Sheet 2 dGAW. 5/7546144 July 21, 1942. .MQC. HANSON EI'AI.

METHOD OF AND APPARATUS FOR CONTROLLING CONCENTRATION 4 Sheets-Sheet 3 Filed Aug. 5, 1939 lili 2% a U464 M 504014 [IIIIIIIII/III]l/(IIIIIIIIII(11% July 21, 1942. M. c. HANSON ETAL METHOD OF AND APPARATUS FOR CONTROLLING CONCENTRATION 4 Sheets-Sheet 4 wwwraes: M4P77/V a. AMA/30A! uAa/m/ M 3mm Patented July 21 2,299,411 METHOD OF AND APPARATUS FOR CON I TROLLING CONCENTRATION 0. Hanson, .BiversideQand Sagan 'N.

Shar'ma, Los Machin Angeles,-alil., assignors to Food cry Corporation, San Jose, Calif., a corporation of Delaware Application August 5, 1939. Serial No; 288,626

, 2 Claims. This invention relates to the art of handling various concentrations of one material in another and has particular utility in the treating of agricultural produce with gas to retard the growth of decay organisms therein.

Extensive studies in research have been made in the effort toeliminate decay of fresh fruits and vegetables while these are being harvested, stored and shipped incidental to their being packed and marketed. Although much progress organisms, a considerable portion of several important crops is still lost "due to decay before the crop can be marketed. The citrus crops are particularly vulnerable to attacksof blue mold and green mold, lemons being particularly susceptible to these during the period of 7 several months which most 'of the lemon crop is stored while it ripens. When taken out of this storage to pack the fruit, the lemons have to be carefully picked over: and the rots separated out from the good fruit before the fruit can be packed. Even when this is done, a certain amount of contamination of the good fruit is bound to result by the powdery mold spores which sift from the infected with the lemons adjacent fruit into contact thereto.

An effective method has been developed for treating fruit in storage, without disturbing this period of their storage as will substantially prevent the development of decay in the fruit. This gas treatment has been expensive to use,- however, because of the narrow limits within which the concentration of gas could be used so that this would effectively control the decay organisms in the fruit treated and yet not be so strong as to burn the fruit. Prior to the present invention the concentration of gas in these treatments has been maintained by an expert attendant periodically checking the concentration of gas in the room in which the treatment was being carried on and altering this concentration in accordance with his findings.

It is an object of the present invention to pro 'vide a method of and apparatus for controlling the concentration of one -material. in another which is adapted to be used lathe treating of fresh fruits and vegetables with gas so that this can be done relatively inexpensively and with organisms will be attained and that the fruit an not be burned by an excessive'concentration of gas in the atmosphere.

Another object of the present invention is the provision of amethod of and apparatus for producing a gas within a closed treating chamber and controlling the production of the gas in response to chamber.

Other objects and advantages of thepresent has been made in this battle to control decay invention will be made manifest in the following description taken in connection with the accom- Danying drawings, in which:

Fig. 1 is a perspective view of a fruit treating chamber, portions thereof being broken away to show themanner in which the gas generator of this invention is used.

Fig. 2 is anenlarged, front elevational view of the gas generatonportions being broken away to disclose the structure thereof.

Fig. 2A is an enlarged fragmentary view of the as generator of our invention.

Fig. 3 is a side elevational view looking in the direction of the arrow 3 of Fig. 2.

Fig. 4 is an enlarged vertical sectional view takenon thelineHofFig.2.- T Fig. 5 is an enlarged horizontal sectional view taken on the line 5- -5 of Fig. 2.

Fig. 6 is an enlarged vertical sectional view taken on theline 8-1-8 of Fig. 3 and showing the valve control apparatus included in the gas gen- 'erator of our invention. Figs. 'I'and 8-are fragmentary, vertical sec-v tional views taken on 'the lines 1-1 and -8 8 of Fig. 6.

Fig. -9 is a fragmentary view looking-in the direction of the arrow 9 of Fig. 6.

Fig. 10 is an enlarged vertical sectional view through a portion of the"control apparatus shown in Fig. '6.

Fig. 11 is an electrical wiring diagram of the control apparatus shown in Fig. 6.-

v Fig. 12 is a diagrammatic enlarged fragmentary detailed view illustrating the mode by which a testing liquid is passed through the atmosphere.

in the fruit treating chamber to produce a uniform partial exposure of successive portions of said liquid to said atmosphere.

Referring specifically to the drawings, a "gas enerator lll, comprising a preferredembodiment of the apparatus of the present invention is shown enerally in Figs. 1 2 and 3; the unit In including a frame ll, valve control apparatus l2 and assurance that the desired action on the decay gas generating apparatus l3.

the relative amount of gas in they The frame 11 28 is a box 25 having a removable cover 21.

The valve control apparatusfz The valve control apparatus I2 includes a housing 38 supported as shown in Fig. 3, by brackets 3| mounted on the horizontal angle irons 23 and 24. Provided on the front side of the housing 38 is a cover plate 32 having a jewel 33 mounted thereon. Threaded into the upper wall of the housing. 38, as seen in Fig. 6, is a funnel 35 having a central bore 35, a conical depression 31 at its upper end and a nipple 38 extending from the lower end thereof. Provided on one side of the housing 38 is a case 48 containing a pair of electrically operated valves 4| and 42. Each of the valves 4| and 42, shown in Fig. '7, includes a central tube 43 having a bore 44, the tubes 43being formed of a corrosion-resisting material such as hard rubber. Threaded onto the lower end of each of the tubes 43 is a stop cock 45 having a central bore 45 and a nipple 41. Extendin transversely through each of the stop cocks 45 is a manuallyoperable valve cylinder 48. Movable vertically within the bore 44 of each of the tubes 43 is a valve plunger 58, the latter comprising a hollow glass cylinder 5| having an iron core 52 therein. As shown in Fig. '7, the plungers 58 fit loosely within the bores 44 and have ground,

conical points at their lower ends'which fit on ground seats in the stop cocks 45 so as to close the bores 45 thereof when the plungers 58 are in their lowermost positions. Surrounding each of the tubes 43 is a solenoid 53, the latter, when electrically energized, raising permit liquid to flow through the tubes 43 as described hereinafter.

Mounted at one side of the housing 38, as shown 'in Fig. 6, is a potentiometer 55 adjustable by means of a knob 55 having a pointer 51 registering with a segmental, graduated dial 58 fixed on the housing 38 as shown in Fig. 9.

Supported within the housing 38 (see Fig. 6) by lugs 58 is a panel 5| upon which the various electrical elements for controlling the valves 4| and 42 are mounted. Provided on the upper portion of the panel 5| is a pair of housings 55 and .55, the former containing a conventional photo-electric cell 61 and the latter having an electric exciter lamp 58 mounted therein. As seen in Fi 10, the innermost walls of the housings 55 and 55 are formed to provide ali ned, threaded openin s 18 and 1| respectively. Screwed into opening 18 is a collar 14 adapted to support one end of a light filter cell 15 having glass end walls 16 and being filled with a solutionof copper sulphate. Threaded into the opening 1| of the housing 55 is a collar 18 having a pair of lenses 88 mounted therein. Supported at one end thereof by the collar 18is a scanning cell 8| having glass end walls 82 and inlet and outlet tubes 83 and 84 respectively, the tube 83 being connected to the nipple 38 of the funnel 35 by a rubber tube 83a. Threaded on one end of the filter cell 15 and scanning cell. 8/I is a ring 85.

the plungers 58 to Mounted on the panel 5| between the housing 55 and 55 is a pilot light 88 positioned to illuminate the jewel 33 in a manner to be described hereinafter.

Fixed on the panel 5| below the housing 55 is a micro-amp" relay 88 similar to the device disclosed in U. S. Patent No. 2,062,915 issued Dec. 1, 1936, re A. H. Lamb. The relay 90, shown diagrammatically in Fig. 11 of applicants drawings, includes a moving coil 8| to which an oscillatin switch arm 82 is fixed, the latter having a permanently magnetized contact 83 thereon. Positioned for engagement with the contact 83 of the arm 82 is a stationary permanently magnetized contact 84, the arm 82 being normally urged into engagement with the contact 84 as shown in Figs. 6 and 11 by a hair-spring (not shown). -Also provided in the relay 88 is a solenoid 85 having a vertically movable core 85 for actuating a pair of fingers 81 as described hereinafter. As shown in Fig. 6, a pointer 88 is provided in the relay 88 for registration with graduations 88. The pointer 88 normally remains stationary and is adjustable manually to increase or decrease the tension exerted on the switch arm 82 by the aforementioned hair-spring.

Mounted on the panel 5| is a double coil, interlocking relay I88 and a single coil, control relay I8I, these being shown diagrammatically in Fig. 6. The interlocking relay I88 includes coils I84 and I85, the coil I84 operating a pivoted lever I85 and the coil I85 actuating a latch lever I81. Operated by the lever I85 is a double switch having arms I88, 8 and stationary contacts III and I I2. The control relay I8| includes a coil II5 for actuating a lever I I5, the latter operating a switch arm l'l1having stationary contacts H8 and 8 provided on opposite sides thereof. M

Mounted on the lower portion of the "panel 5| as shown in Fig. 6 is a motor driven switch mechanism I25 including a frame I25 having a synchronous electric motor I21 mounted thereon. Driven by the motor I21 through a speed means of screws I38.

counterbored to receivethe adjacent end of the 1 As shown in Fig. -1, a control box I42 is provided for controlling the supply of current to the valve control apparatus I2 of the gas generator I8. The box I42, as shown diagrammatically in Fig. 11, includes a pilotlight I43 and a timecontrolled switch I44, the latter being automatically opened as described hereinafter by a clock mechanism I45 having a pointer I45 and switch actuating arm I41.

Mounted on the back side of the housing 38 as shown in 'Fig. 3 is a housing I58 containing a transformer |5| and a rectifier I52 as diagrammatically shown in Fig. l1. The transformer |5| comprises a primary, high voltage coil I53 and a secondary, low voltage coil I54. The rectifier I52 includes direct current terminals I55 and and alternating current terminals I58 and The electrical system of the valve control apparatus I2, as shown in Fig. 11, includes four separate circuits: a v.A. C. circuit obtained from a suitable source of supply; a 10 v.A. C. circuit obtained from the transformer |5|; a 10 v.D. C. circuit obtained from the rectifier I52;

. I69 respectively.

switch arm I I1 ,of the relay "I I-.

and. a micro amp circuit generated by the photo-electric cell 61-, these four circuits being now described in the onder above named.

The elements energized by the 110 v. circuit include the pilot lights 88 and I 43, the motor I21 and the primary coil I53 of the transformer The 110 v. current is supplied from'any' suitable 1 source to-the apparatus I2 by lead wires|63 and I64 which lead to the coil I53 oi thetrahsiormer l5l, the wire I64 being interrupted by the switch I44of the control box I42. Connected to and extending item the lead wire I63 to one terminal of each of the pilot lights 86 and I43 is a wire I65.

the coil II5 being .ioinedto the switch arm 92 of the relay 90 by a wire I95. The podtionoi the. switch arm' .I I1 02 the relay I0l determines which oithe two coils I04 and I65 is to be energized by the v.-D. C. circuit'as hereinafter de-' scribed.

The micro-amp circuit between the photoelectric cell 61 and the relay 90 as seen in Fig. 11,

' comprises a pair of wires I96 and I91 leading to The circuit to the'pilot light 88 is completed by a wire- I66 extending from the lead I64 to the remaining terminal of the light 88 and-on to the stationary contact III or the relay I00, the light 88 being illuminated'whenever the-switch I 46 is closed. The light 88 illuminates, the jewel 33 to indicate when the timing switch I44 is closed. Extending from the remaining terminal oi the pilot light I43 to the switch arm I08 oi the relay I00 is a wire I61. Extending from the lead wires I63 and I64 to the motor I21 are wires I66 and The elementsoithe 10 t. A. c. circuit .dis-

former I5| are the rectifier I52 and the exciter lamp 68. Connecting opposite ends of the coil I54 with the terminals I58 and I59 0! the rectifier I52 are wires I10 and HI respectively and extending from the wire "I to one terminal of the moving coil 9| oi the relay 90, the 'wire I91 embracing the potentiometer 55. a Included in the valve control apparatus I2 is a jar 200 provided in the box26 as shown in Fig. 2. The mouthoi the jar 200 is closed by an airtight cover 20| having a hole 202 formed there-- through. Mounted infthe hole 202 is a gas fllter ing tube 204' containing layers 01' glass wool 205, charcoal 206and granules 201' of mixed potassium iodide and starch. Supported bya stopper 208 at the bottom of the jar200 is a capillary I tube 209, the lower end 2I0 thereof being dis-.

posed above the funnel as shown in Fig. 2, and Y closed by a removable cap 2|0a when the-unit I0 charged by the secondary coil m of the transthe exciter lamp as is a wire m, the remaining terminal 'of' the lamp 68 being connected by a wire I13 to the micro-switch I35,.the latter being joined by a wire I14 with the wire I10 oi the 10 v. A. C. circuits The elements of the apparatus I2 energized by the 10 v. D. C. circuit include the solenoids 53 oi the valves 4| and 42, the solenoid 95 of the micro-amp" relay 90, the coil 5-61 the relay IM and the coils I04. and I05 of the relay I00.

- Connectingone end of each of the valve solenoids 53 with theterminal I51 of the rectifier 52- is a wire I18, the opposite ends 01' the being connected to the switch arm IIO of the relay I00 by a wire I19. The circuit to thevalve solenoids 53 is completed by a wire I80 extending from the terminal I56 of the rectifier I52 to the stationary contact I I2 of the relay I00, the latter and to one end of the solenoid 95 of the relay 90. The opposite'end of the solenoid 95 is: connected to a wire I83 which extends to one terminal of solenoids 53 is not in use. The upper portion of the tube 209 is coiled as shown in Fig. 5 so as to provide a substantial length of tubing in a relatively small space. The jar 200 is filled with a solution 2 such as orthotolidine which darkens in color when subjected to chlorine containing gases as described hereinafter.

Mountedon the-horizontal frame member 24,

as seen in Figs. 2 and 3 is a container M2 for receiving the solution 2 after the latter, passes from the scanning cell 8| through the outer tube 94, a rubber tube 2|3 shown in Figs. 3 and 6 being j provided to conduct the solution into the coni tainer 2 II.

serving to energize the valve solenoids 53 in a manner described hereinafter. Connected to'the terminal I56 of the rectifier I52 is a wire I82, the latter leading to the contact 94 of the relay -90 the cam-operatedswitch I31, the other terminal of the latter being Joined with the terminal I51 oi the rectifier I52 by a wire I 84. "The-l0 v; D. C.

circuit from the'rectifier I52 tothecoils I04 and v I05 of the relay I00. includes awire.l66 extending from the-terminal I56 of the rectifier. I52 to the I Connecting the stationarycontacts H8 and "90f. the relay |0| with one end of each oi the coils"I 04 and I05 of the relay I00 are wires-|88 'andI89 respectively,

the opposite ends of the coils I04and I05 being jointly connected to a wire I90 extending toone terminal of the-cam-o'perated switch m, the other terminal of the latter being-Joined by a wire|9| with the terminal I51-oi the rectifier i52.

Connected to one end of the coil l I 5 oi the relay llll isa wire |94,-the latter-leading t0 th'terminal I51 oi the rectifier |52,the oppositeend of liquids dropping from the tubes 'The gasg'enerating apparatus, 13

The gas-generating'apparatus I3 .includes a jar 220 positioned in the box 26 as shown in Fig.- 2, this jar containing asolution 22I- of analkaline .hypochlorite such as sodium hypochlorite. Ex-

tending from thebottom of the jar 220 is a tube 222 for conducting the solution 22I to the valve 4| within the housing 40 (see Fig'. 7). Adjacent. the jar 220 is a smaller jar 224 containing hydrochlorlc acid 225,- the latter being conducted to the valve 42'by a tube 226. The volume of the jar 224 is approximately half that of the jar. 220 as one part ofacid and two parts of hypochlorite are required to produce hypochlorous acid gas.

Provided on the base l5, as shown in Figs. 2 and 3 is a crock 230 having a spring bracket 23I slipped over the upper edge thereof. Supported.

by the'bracket 2'3I (see Figs. 2 and 2A) is a chemical mixer 232 including a non-corrosive body 233 comprised of .a head 234 and stem 235. Extending through the head 234 are capillary tubes 236 and 231, these being connected wit the cocks 44 of the valves 4| and 42 .by rubber tubes 2 38 and 239 The bore of the capillary tube .236 is larger than the bore of the tube 231 in" order to feed the solutions 22L and 225/in the. aforementioned proportion of two-to-onje. Provided on the stem 235 of the body 233 is a series- .closed chambers, the-most common of these'be- Ling gassing rooms especially built in packing ceiling.

' Hi this :unownmrrgc. as

apart at regular tion or light which houses for this purpose, and box cars inwhich the fruit has been loaded for shipment. Fig. l diagrammatically illustrates the gassing of fruit by the apparatus ill in a specially built gassing room as are commonly provided in fruit packing houses. This'gassing room R. has walls I", aceiling 2N and a removable side wall formed by a canvas flap 1. Mounted on the ceiling 2 are fans 1, two of which are preferably provided at each side of the room It. The fruit to be treated is stored in room It in stacks S of fieldboxes which are preferably arranged in spaced relation to permit circulation of the treating gas to the lowermost boxes in the stacks. In arranging the truit in the room R, a space is left in the stacks of the boxes to accommodate the generator Eland a portable blower 25G.

The blower I5! provided to thoroughly mix v the gas produced by the generator I?! with theair in the room B. As this gas is generally heavier than air, the blower functions to best advantage in picking up the. -air and gas located close to the floor at a point adjacent the genelater [I and directing this upwardly toward the After everything has been arranged as shown in Fig. 1 for gassing a room full of fruit, the generator ill is set in operation and the fans I and blower III started. After this is done, the canvas wall 2 maybe lowered and the generator EU will automatically gas the fruit in the room R for a predetermined period of time, maintaining a substantially uniform concentration of gas in the room and at the end of this period will automatically cease operation:

Before describing the operation of the generator' 2 in detail, this operation will be briefly outlined as follows:

v To set the gas generator [I in operation, the operator rotates the pointer E of the clock mechanism "5 in a clockwise direction (see Fig; pointer indicates on the ace of the clock .the number of honrs'which it is desired that the generator continue in operation to maintain a given concentration 'of gas in the room It. This closes the circuit as will be dehereinatter, which energizes the valve control apparatus [2. At the same time that the the generation of gas, and so that when the gas;

. concentration falls clock mechanism is thus the operator removes the cap lila- Irom the lower end I of the tube ill to permit the orthotolidine solution I to feed from the jar as through the capillary tube as and to drop slowly the drops of ortlmtolidine form at lower extremity III of the tube Ill and drop into the drops are exposed to the atmosphere in the in color while thus exposed, in direct prop'ortiontothe concentration of thetruittreating gasinthe atmosphere; A!- terthe scanning cell has become n I w ,thisescapestherefromthroughtbe tubes N and itifromwhenceitflowsintothe ll! showninm Z and 3.

Theapparatns llinclndcsamechanism which lfihtstheexcite'rlarnp for short periods preferablyabouttensecondsinlengthandspaced intervals of preferably about threeminutcseachhramanncr hereinsiter. Whilethelamp Ilia thus lighted, a portion of the light passes throughthecelltlandthelightnlterliandimriccellfl. 'rheporthusreaches thefphoto-electricecllivarieshrinvemproportiontothedarkintotheiiunnel thehmnel lblasshowninliigii.

tobedescribcd the latter two.

15 throws a r the atmosphere surroundin I amount of light reaching the photo-electric cell to stop generating gas; or,

a i so that when the concentration before automatically ointer MI is thus- --cloced, the pilot ness of the coloro! the solution ill within the scanning cell 81. As the darkness of the color of the solution 2 within this cell varies in direct proportion to the concentration of gas in g the generator II, the

61 when the exciter lamp 8 is lighted, is thus seen to be inversely proportional to the concentration of gas in the atmosphere. sible, by the reaction of the photo-electric cell to the amount of light reaching it during each period that the lamp 8 is excited, to exercise a control function which is accurately and directly related to the concentration of gas in the atmos phere.

In the apparatus II, the photo-electric cell G1 is employed for controlling the production of gas by the gas generating apparatus [3. This control is exercised upon each excitement of the lamp I to do one of three things: first, either to start the gas generating apparatus [1' generating gas; or, second, to cause the generating apparatus [3 third, to maintain the status quo. g

The production of gas by the gas generating apparatus [3 results from the mixing of portions of the gas forming liquids Hi and which are permitted to pass through the valves I and 42 and discharge downwardly over the mixing discs 2". The production of. gas isthus started by opening the valves-ll and 42 and stopped by closing these valves. These valves are controlled so as to start, stop or maintain the production of gas as aforesaid during each ten-second period, of gas within the room R exceeds the predetermined maximum, the valves ll and 42 are closed, thereby stopping below a predetermined minimum, the valves ll and are opened to start the production of gas and sothat when the gas concentration in the room R is between said maximum and minimum the gas generating apparatus I1 is permitted to stay as it was, whether it was generating or not generating gas.

Passing now to a more detailed description of the operation of the generator II, it will be assumed that the pointer l of the clock mechanism i has been; set inia clockwise direction as already described until on the face of the clock, the number of hours which it is desired that the generator function shutting down.

out of engagement with thelattcr to close. thus 7 tel-apparatus l2. As soon as the switch I is light I! lights, indicating that apparatus [2 is energized and the motor it! the shaft l2! continuomly at the start! and drives 55 R. P. H.

The cams III, I" rotate one revolution the direction indicated by the arrows thereon in Fig. 11, and the lobes Illa, Illa and ills of the cams momentarily close the switches l3, l3 and [TL-respectively, the

liaJhtbelobe maorwcm thelobes "hand "is caus- Ill and iflonthecamahait Alahownin Maternal-than llltocloae'priortotheswitchcsiaandlli'andtorunainclocedlma rtlnn Clolillttheawitch iliclosesthe ficircuittothe-eaciterlampum beamotlightthroughthescanningceli Itisthuspos this pointer indicates,

energizingthevalve coneverythreeminutesin.

each revolution of to swing the fingers 91 inward, the latter cen- 61. the latter discharging electrical current and energizing the moving coil of therelay' 00.

Immediately after the lamp 08 is lighted by the closing of the switch I35 by the cam I30, the switch I21 is momentarily closed by the cam I32 to reset the switch arm 92 of the micro-amp relay 00. Closing of the switch I31 closes the v. D. C. circuit from the rectifier I52 to the solenoid 05 of the relay 00 causing the core 96 tralizing the switch arm 92 and releasing it as soon as the switch I3! is permitted to open.

t l, filter cell I5 and into the photo-electric cell shown in Fig.l1'with the contacts 93 and 94 a I engagement. Engagement of the contacts 03 and 94 closes the circuit from the rectifier I52 to the When the moving coil 9| is energized by current from the photo-electric cell '01, the coil 9| tends to swing the switch arm 92 rightward away from the magnetic contact 94 against the influence of the aforementioned hair-spring (not shown). When the gas concentration in the room Ris below the aforesaid minimum, the

orthotolidine solution-in the cell 8| isrelatively clear, thus allowing a substantial amount of light to pass from the lamp 68 to the photo-electric cell 61. The current generated by the photoelectric cell 61 is thus s'ufiicient to cause the moving coil 9| of the relay 90 to maintain the switch arm 02 out of engagement with the contact 94 thus breaking the circuit to the coil 5 of the relay IN and permitting the switch arm III of the latter to remain in engagement with the contact II9. Wheli the switch arm III is inthis position, the circuit is closed through the wire I89 to' the coil I04 of the relay I00 and when the cam-operated switch I36 is closed by the. cam

I3| the circuit from the rectifier I52 to the relay a I00 is completed to energize the 'coil I04. The Y coil I04 moves the lever I06 which lifts the switch arms I09 and H0 upward against the contacts IIIand II2 closing the circuits to the pilot light I43 and the solenoids 53 of the valves 4| and 42',

the plungers 50 of the latter being lifted by the magnetism of the coils 53 allowing the hypochlorite HI and acid 225 toilow into the tubes 222 and 226 respectively and into the mixingdishes 238 where the gas is formed;

The lever I06 of the relay I00 is retained in operative position after the circuit to the coil I04 is broken by the latch lever I01 in order-to maintain the valves 4| and 42 in open position. At three-minute. intervals, the switches I35, I36

and I31 are actuated by the cams I30, 'I3I and I32 respectively, and as long as theconcentration of gas. in the room Ris less than the aforesaid minimum, the apparatus I2, upon each such exceeds the aforesaid maximum, the production v of gas by the generator'I0 is stopped in the following manner: When the orthotolidine darkens in color beyond a given point, indicating that, the proportion of gas in the room R has exceeded the maximum concentration desired, the amount of light received bythe 'photo-electriccell 61 from the exciter lamp 60 is reduced causing a proportional reduction in the amount of current generated by the cell 61. When the switch arm 92 of the relay 90 is again centralized and released by the fingers 0'! in response to momentary closing of the switch I31, insufilcient current is received by the moving coil 9| to overcome the-force "exerted on the switch arm 92 by the aforementioned hair-sp released, s

g and the arm 92, upon being H6 and 'move the'switcharm. III into engage-' ment with the contact I I8, thus'joining the wires I86 and l80'enabling the coil I05 of the relay I00 to be energize'd. when the switch I36 is closed-by the cam I3I. When the coil I05 is thus energ'iz'ed, the latch lever |0I'is movedout of engagement with the lever I06 causing the switch arms I00 and H0 to move downward away from the contacts III and H2 so as to break the circuits 'to the pilot light I43 and valves 4| and 42, the

latter stopping the fiow'of the gas forming liquids 22| and 225.

During the entire period of treatment of the fruit in the room R; the control apparatus I2 of the generator I0 checks the concentration of gas every three minutes in the manner above described, thus insuring a sufiicient concentration oi gas to efiectively treat the fruit and preventing such a concentration of gas as would injure ment of the potentiometer 55 (see Fig. 11') regulates the amount of current permitted to pass from the photo-electric cell 61 to-the microamp'relay 90.

The'=hypochlorous acid gas-formed by the gen- 'erator I0 is considerably heavier than air and the function'of the blower 250 is to blow the gas from the vicinity of the generator II! to the upper portion of the room R to permit the gas to settle down between the stacks S or the blown down by the ceiling fans 248. It is also noted that if the gas were not'drawn from the generator I0 the orthotolidine solution would soon become darkened so as to stop the generation of gas before 'the room It is uniformly provided with the desired concentration of gas.

When the pointer I46 of the clock mechanism riod, the switch I44 is automatically .opened so as to stop the operation of the generator I0. The herein disclosed method and apparatus, while particularly useful in treating citrus fruits as specifically disclosed, is equally capable of broad application to edible or fresh farm or agricultural products of all kinds as contemplated in thespecification. Therefore-the term fruit as used in the claims is not to be construed as limiting-the claims to any garticular type of edible. product.

We claim as our invention:

1. In a method of treating fruit by subjecting thersame to contact with controlled concentration of liberated gas within the atmosphere ofv a closed chamber, the steps of. controlling said gaseous concentrationcomprising passing relatively small increments of a liquid testing agent capable of color reaction by contact .with said gas through the gaseous atmosphere in said chamber at a uniform rate to effect a substantially unis to the position in which it is form exposure of said liquid incrementsto said,

tion in said chamber, and varying said concentration in accordance with said test 2. In amethod of treating fruit by subjecting: the same to contact with controlled concentration of liberated gas within the atmosphere of a closed chamber, the steps of said laseous concentration comprisinz posing by gravity relatively small increments of a liquid testing agent capable of color reaction by with said gas through the gas permeated atmosphere insaidcha'mher atauniiormrateto effect asuhstantially uniform exposure oi? said liquid. increments to said atmosphere for a. predetermined time, collecting said liquid increments and confining the same against. further contact 15 chamber predetermined limits.

with said gaseous atmosphere, maintaining said collected and con-fined liquid in a pool. of substantially uniform size by providing an overflow therefrom, photo-electrically detecting at predetermined intervals the degree of opacity to lightof said pool of collected confined liquid by reason. 0t its change in color to determine the degree of gas concentration. in. said'chamber, and

controliinz the liberation of gas to the chamber atmosphere in accordance with the: concentration thereof as thus detected, whereby to maintain theiiberated fruit treating gas in said mom m smm 

